Process of sintering



FILED APR; 20, 1921- Patented Feb. 13, 1923..

THOMAS J. DAVIS, QF DUQUESNE, PENNSYLVANIA.

.raoonss' or smrsar'no.

Application filed April 20, 1921. Serial No. 462,854.

To all whom it may concern.

Be it known that I, TnoMAs J. DAVIS, a citizen of the United States, and resident of Duquesne, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Process of Sintering, of which the following is a specification.

This invention relates to sinterlng blast furnace flue dust, finely divided ores and similar combustible, metal bearing materials or metal bearing materials to which combustible material is added preparatory to sintering. While not necessarily limited to such apparatus my improved process 1s particularly adapted for use with slntermg apparatus of the down-dratt type and embodying a foraminous b0tl3( )m, \\'1tll means for passing a current of air, in quantities sufiicient to support combustion and slnter the material, through a body of material located in the sintering pan.

Heretofore the fora-ruinous bot-tom oi the sintering apparatus has been covered with a relatively thin layer of refractory material, lumps oi limestome usually belngused. This layer of lumpy refractory material forms a porous hearth which directly supports the body of material to be smtered.

In the sintering operation the porous hearth of refractory material, or the 1112.101 portion thereof, becomes an integral part of the mass of sinter, and is removed from the pan with the sintered mass. metal, this refractory material is a dlluent. which lowers the metallic content of the sinter and when limestone is employed, it slakes when the highly heated mass of sinter is quickly cooled by quenching with water, as is. done with each successively formed quantit of 'sinter immediately after lts removal rom the sintering pans.

One object of my invention is to provide an improved process wherein a porous bed is provided to support the materials to be sintered without the use of refractory materials and whereby dilution of the sinter heretofore caused by the use of refractory mate, rial in forming the porous hearth is avoided and made unnecessary.

A further object is to provide a smtermg process having a novel series of steps wherebv the time consumed in sintering a given ainount of material is materially shortened.

Referring now particularly to the drawings, forming part of this specification, Figure 1 is a sectional side elevation of a sinter- Not being 1 ing pan adapted for use in carrying out my invention, and'Figure 2 is a sectional end elevation on the line HH of Figure 1.

In the accompanying drawings, the numeral 2' designates a-sintering pan which is arranged to tilt or'roc-k about a horizontal axis, opposite ends of this pan being provided with hollow trunnions 3, 3, by which the pan is rotatably. mounted in suitable trunnion bearings.

The pan 2 has a bottom 5, sides 6, and integrally formed ends 7 ,the hollow trunnions 3, 3 opening into the pan through the end walls of the pan. At an intermediate point in the hei ht of the side walls of the pan is a series of grate sections 8 having elongated .apertures'therein. The grate sections 8 are supported vertically by transverse girder supports 9 having apertureslO in their Web port-ion.

The outer ends of the hollow trunnions 3, 3, are connected to one end of suitable conduits 11, which are adapted to have their other end connected to an exhausting device (not shown) for creating a suction, thereby drawing the gaseous products of combustion through the grate sections 8, and along the pan beneath the grate.

A porous hearth 12 which is loosely positioned on the grate sections 8 is formed of a thin layer of coarse particles of previously sintered material. A mixture of flue dust or similar material and fine particles of previously sintered material is then placed in the sintering pan on top of the hearth 12 and leveled, forming ready to be sintered.

It is; the practice to separate the coarse and fine portions of the sinter by screening, the

coarse portions being sent to the blast furnace or other place of utilization, and-the a bed, 13, of'material fines being mixed with the 'finely divided I flue dust or other material being used in the sinter ing operations.

In the operation of my improved process the screenings resulting from the first screen-- ing' operation, just before described, are

the finer particles thereof. The coarser porjagain screened toseparate the coarser from tions are then used in making the porous hearth 12, being spread over the foraminous grate 8. The. finer particles are mixed'with' v the flue dust or other material used in forming the bed 13. As the screenings or sinter will be coarser than the flue dust, a more porous body will be formed by the mixture,

thereby facilitating the passage of air or products of combustion through the bed of material being sintered.

The mixture of the fine particles of sintered material and fine dust or other material to be sintered is charged into the pan 2 and leveled, off forming the bed 13 in the usual manner. The bed 13 is then ignited on its upper face and the exhaust blower is started so as to draw the air or products of combustion downwardly through. the bed 13 into the space below the grate sections 8 and out through the conduits 10.

By the use of previously sintered' material to: form the porous hearth 12, a sinter is formed that will not disintegrate and one that contains no undesirable constituents for charging into the smelting furnace.

Also, by combining the fine particles of previously sintered material .With the material to be sintered, the porosity of the bed 13 is increased, the passage of air or products of combustion therethrough is facili tated, and the time necessary to sinter a given quantity of material is materially lessened. 4

The advantages of my invention, as Will be readily appreciated by those skilled in the art, arise from the use of a non-refractory material in forming the porous hearth and in utilizing the: finely divided sinter to make. the more finely divided flue dust less dense in preparing for the sintering opreations.

I claim 1. The process of sintering flue dust and similar combustible material which includes first forming a porous hearth of coarse sintered material, then forming a bed of the materials tobe sintered on said hearth, and finally igniting the so-formed bed.

2. The process of sintering flue dust and similar combustible materials which includes one face of the so-formed bed and thereby sintering the mass.

3. The process of slntering flue dust and similar combustible materials Which includesforming a porous hearth of comparatively coarse portions of previously formed sinter, mixing a quantity of finer portions of previously formed sinte-r with the flue dust, forming a bed of said mixture upon said porous hearth and then sintering the materials forming said bed.

4. The process of sintering fine dust and. similar combustible materials Which includes separating the fines from the coarser portions'of previously madesinter, again separating said screened materials into its coarser and finer parts, forming a porous hearth on the perforated bottom of a sintering pan with the coarser grade of the screened screenings, mixing the finer grade of the screened screenings with the combustible materials to be sintered, forming a bed of the mixture upon said porous hearth, and then sintering the mass.

5. The process of sintering flue dust and similar combustible materialswhich includes screening sintered fine dust to separate the fines therefrom, re-screening the fines to separate the finer from the coarser portions thereof, forming a porous hearth of the coarser screened screenings, mixing-the finer 7 portions thereof with the materials to be sintered, and forming a bed of said mixture upon said porous hearth preparatory to sintering the mixture.

In testimony whereof, I have hereunto set my hand.

THOMAS J. DAVIS. 

